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Autor Luis Aina, Alfredo |
Documentos disponibles escritos por este autor (102)
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We address the propagation of the spin along classical trajectories for a spin-1/2 particle obeying the Dirac equation with scalar potentials. Focusing on classical trajectories as the exact propagation of wave-function discontinuities, we find [...]texto impreso
The states generated from the vacuum in two parametric down-conversion crystals with aligned idler beams are studied. It is shown that after a measurement of the photon number in some of the modes, the emerging states can be related to SU(2) and[...]texto impreso
We develop an SU(2)-invariant approach to the depolarization of quantum systems as the effect of random unitary SU(2) transformations. From it we derive an SU(2)-invariant Markovian master equation. This is applied to several quantum states exam[...]texto impreso
We provide evidence that the uncertainty in detection of small and deterministic phase-shift deviations from a working point can be lower than the Heisenberg bound, for a fixed finite mean number of photons. We achieve that by exploiting nonline[...]texto impreso
Weak-measurement-based experiments (Kocsis et al., 2011) have shown that, at least for pure states, the average evolution of independent photons in Young's two-slit experiment is in compliance with the trajectories prescribed by the Bohmian form[...]texto impreso
We present a simple multimode analysis of the Zeno and anti-Zeno effects in spontaneous parametric down-conversion. In this process the input vacuum is an unstable state decaying into a reservoir of down-converted modes by emitting a pair of pho[...]texto impreso
We examine the appearance of Zeno and anti-Zeno effects when the unitary evolution of a two-level system is observed. We demonstrate that, contrary to previous claims, the anti-Zeno effect can occur in two-level systems so that the observation c[...]texto impreso
Porras, Miguel A. ; Luis Aina, Alfredo ; Gonzalo Fonrodona, Isabel ; Sanz, Ángel S. | American Physical Society | 2011-11-14We analyze a simple and feasible practical scheme displaying Zeno, anti-Zeno, and inverse-Zeno effects in the observation of wave-packet spreading caused by free evolution. The scheme is valid both in spatial diffraction of classical optical wav[...]texto impreso
Luis Aina, Alfredo ; Gonzalo Fonrodona, Isabel ; Porras, Miguel A. | American Physical Society | 2013-06-20We describe a version of the Zeno effect where the monitored physical property cannot be represented by a standard operator in the system space and the evolution to be prevented by observation is not unitary. This is the case of quantum-state pu[...]texto impreso
Two examples are presented where the photon emission on spontaneous parametric down-conversion is prevented when attempts are made to infer the moment of emission. This inhibition is analyzed in terms of the disturbance caused on the system by t[...]texto impreso
A metastable atomic level can be tendered unstable in a controllable way by coupling it to a decaying state. In this work we carry out a full dynamical analysis of the Zeno effect in this kind of unstable systems, comparing it to the inhibition [...]texto impreso
We describe an experiment in which the rotation of the polarization of light propagating in an optically active water solution of D-fructose tends to be inhibited by frequent monitoring whether the polarization remains unchanged. This is an exam[...]